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. 1973 Feb;51(2):267–272. doi: 10.1104/pp.51.2.267

Simultaneous Influx and Efflux of Nitrate during Uptake by Perennial Ryegrass 1

M A Morgan a,2, R J Volk a, W A Jackson a
PMCID: PMC366248  PMID: 16658313

Abstract

Experiments with intact plants of Lolium perenne previously grown with 14NO3− revealed significant efflux of this isotopic species when the plants were transferred to solutions of highly enriched 15NO3−. The exuded 14NO3− was subsequently reabsorbed when the ambient solutions were not replaced. When they were frequently replaced, continual efflux of the 14NO3− was observed. Influx of 15NO3− was significantly greater than influx of 14NO3− from solutions of identical NO3− concentration. Transferring plants to 14NO3− solutions after a six-hour period in 15NO3− resulted in efflux of the latter. Presence of Mg2+, rather than Ca2+, in the ambient 15NO3− solution resulted in a decidedly increased rate of 14NO3− efflux and a slight but significant increase in 15NO3− influx. Accordingly, net NO3− influx was slightly depressed. A model in accordance with these observations is presented; its essential features include a passive bidirectional pathway, an active uptake mechanism, and a pathway for recycling of endogenous NO3− within unstirred layers from the passive pathway to the active uptake site.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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